This invention relates to gear boxes and transmissions, particularly those used in winches having multiple speeds or gear ratios in one direction of drum rotation.
Two speed winches have long been in existence, wherein a reversal of the rotation of the drive shaft provides a different rotational speed for the drum given a fixed rotational speed for the shaft. Although, the word "speed" is frequently used to describe the operation of a winch drum under the effect of different gear trains, what is actually meant is that the winch can operate with different mechanical advantages. The term "first speed" general means the highest drum speed, which corresponds to the lowest mechanical advantage provided by the winch. This first speed allows the drum to be turned at the fastest rotational speed under conditions of low line load thereby allowing the operator to quickly bring in a line, coil, or rope. The next speed, generally called the "second speed" has a slower drum rotational speed than the first speed and provides a higher mechanical advantage, useful when the line load has increased.
Obviously, because the drive shaft can be rotated in two directions (i.e. clockwise or counterclockwise), it has been simple to design two speed winches wherein the drum rotation in one direction can be operated with two different gear ratios. However, a need has been recognized to provide winches having more than two speeds where there can be a large variation of line loads.
Because winches are frequently used on sailing ships where the loads can vary greatly, and can change quickly, there is a need for multispeed winches that can quickly, smoothly, and automatically change between three or more speeds upon reversal of the drive shaft rotation.
It has also been desirable for winches that are used on sailing craft to be adaptable to having the direction of its drum rotation changed to accommodate different locations on the craft, that is, allowing the line to be pulled from the most convenient position (i.e., having the drum rotate clockwise or counterclockwise).